From de8a529d349aebb344979609055f123c196ccfe3 Mon Sep 17 00:00:00 2001
From: Doug Gilbert <dgilbert@us.ibm.com>
Date: Mon, 12 Sep 2011 12:47:53 -0500
Subject: Mechanism to detect low memory and cast out older page

Change-Id: Icce8e01f3d1cd2942f2b9ff802993da0441535ee
Reviewed-on: http://gfw160.austin.ibm.com:8080/gerrit/344
Tested-by: Jenkins Server
Reviewed-by: A. Patrick Williams III <iawillia@us.ibm.com>
Reviewed-by: Douglas R. Gilbert <dgilbert@us.ibm.com>
---
 src/include/kernel/pagemgr.H | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

(limited to 'src/include/kernel/pagemgr.H')

diff --git a/src/include/kernel/pagemgr.H b/src/include/kernel/pagemgr.H
index eeed535e0..6cb6fefc4 100644
--- a/src/include/kernel/pagemgr.H
+++ b/src/include/kernel/pagemgr.H
@@ -27,6 +27,8 @@
 #include <limits.h>
 #include <util/lockfree/stack.H>
 #include <kernel/vmmmgr.H>
+#include <builtins.h>
+#include <kernel/console.H>
 
 /** @class PageManager
  *  @brief Manages the allocation of memory pages.
@@ -40,6 +42,12 @@ class PageManager
 	static void* allocatePage(size_t n = 1);
 	static void freePage(void*, size_t n = 1);
 
+        /**
+         * Query state for available memory
+         * @returns percent of pages available
+         */
+        static uint64_t queryAvail();
+
 	enum 
 	{ 
 	    MEMLEN = VmmManager::HTABORG,
@@ -55,8 +63,17 @@ class PageManager
 	void* _allocatePage(size_t);
 	void _freePage(void*, size_t);
 
+        /** see queryAvail() */
+        ALWAYS_INLINE
+        uint64_t _queryAvail() const 
+        {
+            return (100*iv_pagesAvail)/iv_pagesTotal;
+        }
+
             /** Statistics on number of free pages (for debug) */
         uint64_t iv_pagesAvail;
+            /** Total number of pages */
+        uint64_t iv_pagesTotal;
 
 	struct page_t
 	{
-- 
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